There is an internal combustion engine capable of using a mixed fuel of gasoline and alcohol. The concentration of the alcohol in the fuel has an effect on the air-fuel ratio control and the ignition timing control. To address this, the internal combustion engine disclosed in PTL 1 is provided with an alcohol concentration sensor on a fuel pipe that connects the fuel tank and the fuel injection valve to each other. As the alcohol concentration sensor, a sensor is used that outputs a signal responsive to a physical property value of the fuel, such as the capacitance depending on the relative dielectric constant of the fuel or the transmitted light amount of the fuel. The internal combustion engine disclosed in PTL 1 can measure the alcohol concentration of the fuel supplied from the fuel tank to the fuel injection valve with the alcohol concentration sensor. Consequently, even if the alcohol concentration of the fuel varies as a result of refueling, the fuel injection amount, the ignition timing and the like can be appropriately corrected in response to the characteristics of the fuel after the refueling.